Effect of IDO1 inhibition on kynurenine levels measured in cell culture supernatants or in mouse plasma samples. A. Human sarcoma tumor cell line was cultured and stimulated with human IFNgamma for 48 hours in the presence of increasing concentrations of reference IDO1 inhibitors – either Epacadostat or Navoximod. Supernatants were then collected for kynurenine content measurement by mean of ELISA (BA-E-2200 Kynurenine ELISA kit). IFNgamma-induced Kynurenine production is dose dependently reversed by both IDO1 inhibitors with a more potent inhibitory activity observed for Epacadostat B. C57BL/6 mice were exposed to LPS (5mg/kg) with and without Navoximod IDO1 inhibitor at 100mg/kg or 200mg/kg. Mice were bleeded on Days 1, 3 and 5 and kynurenine was measured in plasma by ELISA (BA-E-2200 Kynurenine ELISA kit). IDO1 inhibition using Navoximod limits both basal and LPS-stimulated plasmatic level of Kynurenine.